A class of small devices exists that are referred to as micro-electromechanical systems (MEMS). Each major dimension of a MEMS device is generally on the order of 1-100 microns (thus “micro”). MEMS devices typically range in size from 20 μm to 1 mm. The devices often include a central unit that processes data and several components that interact with the outside environment, such as sensors. The usage of MEMS devices has dramatically increased over the past several years as companies have integrated MEMS chips into consumer products, such as cell phones and computers.
Such uses include: as sensors, electrical relays, adjustable-angle mirror devices, variable impedance devices, and devices that perform other functions (such as transducers and actuators).
The types of commercial applications include:
Gyroscopes and accelerometers, such as the gyroscope/accelerometer chips used in cell phones to re-orient the screen when turned 90 degrees and allow users to interact with cell phones in more complex ways. MEMS devices are used as gyroscopes in automobiles and other devices to detect yaw, pitch, and roll. This can be used to deploy a roll over bar or to trigger dynamic stability control. MEMS devices are also used as accelerometers in game controllers, personal media players, and digital cameras. They are also used in personal computers to park the hard disc head, when free-fall is detected, to prevent damage and data loss. MEMS devices have also been used in accelerometers in cars, such as to deploy airbags during a collision.
Microphones, such as microphones in cell phones, head sets, and lap top computers.
Magnetometers, such as magnetometers to perform the compass function in cell phones.
Sensors, such as pressure sensors in car tire pressure sensors or blood pressure sensors. Further, for example, biosensors and chemosensors used in medical- and health-related technologies.
Inkjet printers, such as inkjet printers that use piezoelectrics or thermal bubble ejection to deposit ink on paper.
Displays, such as used in digital micro-mirror devices in projectors or such as for interferometric modulator displays.
Optical switching, such as used for switching technology and alignment for data communication.
Fluid flow, such as for micro-cooling systems.
Although MEMS devices are relatively small, MEMS devices are technologically complex structures that cost more per unit wafer area than CMOS chips to fabricate.
Accordingly, there is a need for devices that are smaller (on the nanoscale rather than the microscale), lower cost, simpler in design, and allow for facile fabrication.